Sexually transmitted infections

Sexually transmitted infections

G.R. Scott

Clinical examination in men


Clinical examination in women

Insets on pp. 412–413 (Perianal warts, coronal papillae, mucopus, inflammation) – see p. 426.

Sexually transmitted infections (STIs) are a group of contagious conditions whose principal mode of transmission is by intimate sexual activity involving the moist mucous membranes of the penis, vulva, vagina, cervix, anus, rectum, mouth and pharynx, along with their adjacent skin surfaces. A wide range of infections may be sexually transmitted, including syphilis, gonorrhoea, human immunodeficiency virus (HIV), genital herpes, genital warts, chlamydia and trichomoniasis. Bacterial vaginosis and genital candidiasis are not regarded as STIs, although they are common causes of vaginal discharge in sexually active women. Chancroid, lymphogranuloma venereum (LGV) and granuloma inguinale are usually seen in tropical countries. Hepatitis viruses A, B, C and D (p. 948) may be acquired sexually, as well as by other routes.

The World Health Organization estimates that 448 million curable STIs (Trichomonas vaginalis, Chlamydia trachomatis, gonorrhoea and syphilis) occur world-wide each year. In the UK in 2010, the most common treatable STIs diagnosed were chlamydia (more than 200 000 cases) and gonorrhoea (19 000 cases). Genital warts are the second most common complaint seen in genitourinary medicine (GUM) departments. In addition to causing morbidity themselves, STIs may increase the risk of transmitting or acquiring HIV infection (Ch. 14).

As coincident infection with more than one STI is seen frequently, GUM clinics routinely offer a full set of investigations at the patient’s first visit (pp. 412–413), regardless of the reason for attendance. In other settings, less comprehensive investigation may be appropriate.

The extent of the examination largely reflects the likelihood of HIV infection or syphilis. Most heterosexuals in the UK are at such low risk of these infections that routine extragenital examination is unnecessary. This is not the case in parts of the world where HIV is endemic, or for men who have sex with men (MSM) in the UK. In other words, the extent of the examination is determined by the sexual history (Box 15.1).

Approach to patients with a suspected STI

Patients concerned about the possible acquisition of an STI are often anxious. Staff must be friendly, sympathetic and reassuring; they should have the ability to put patients at ease, whilst emphasising that clinic attendance is confidential. The history focuses on genital symptoms, with reference to genital ulceration, rash, irritation, pain, swelling and urinary symptoms, especially dysuria. In men, the clinician should ask about urethral discharge, and in women, vaginal discharge, pelvic pain or dyspareunia. Enquiry about general health should include menstrual and obstetric history, cervical cytology, recent medication, especially with antimicrobial or antiviral agents, previous STI and allergy. Immunisation status for hepatitis A and B should be noted, as should information about recreational drug use and alcohol intake.

A detailed sexual history is imperative (see Box 15.1), as this informs the clinician of the degree of risk for certain infections, as well as specific sites that should be sampled; for example, rectal samples should be taken from men who have had unprotected anal sex with other men. Sexual partners, whether male or female, and casual or regular, should be recorded. Sexual practices – insertive or receptive vaginal, anal, orogenital or oroanal – should be noted, as should choice of contraception for women, and condom use for both sexes.

STI during pregnancy

Many STIs can be transmitted from mother to child in pregnancy, either transplacentally or during delivery. Possible outcomes are highlighted in Box 15.2.

Presenting problems in men

Urethral discharge

In the UK the most important causes of urethral discharge are gonorrhoea and chlamydia. In a significant minority of cases, tests for both of these infections are negative, a scenario often referred to as non-specific urethritis (NSU). Some of these cases may be caused by Trichomonas vaginalis, herpes simplex virus (HSV), mycoplasmas or ureaplasmas. A small minority seem not to have an infectious aetiology.

Gonococcal urethritis usually causes symptoms within 7 days of exposure. The discharge is typically profuse and purulent. Chlamydial urethritis has an incubation period of 1–4 weeks, and tends to result in milder symptoms than gonorrhoea; there is overlap, however, and microbiological confirmation should always be sought.


A presumptive diagnosis of urethritis can be made from a Gram-stained smear of the urethral exudate (Fig. 15.1), which will demonstrate significant numbers of polymorphonuclear leucocytes (≥ 5 per high-power field). A working diagnosis of gonococcal urethritis is made if Gram-negative intracellular diplococci (GNDC) are seen; if no GNDC are seen, a label of NSU is applied.

If microscopy is not available, urine samples and/or swabs should be taken and empirical antimicrobials prescribed. A first-void urine (FVU) sample should be submitted for a combined nucleic acid amplification test (NAAT) for gonorrhoea and chlamydia; a urethral swab is an alternative if the patient cannot pass urine. When gonorrhoea is suspected, a urethral swab should be sent for culture and antimicrobial sensitivities of Neisseria gonorrhoeae. Tests for other potential causes of urethritis are not performed routinely.

A swab should also be taken from the pharynx because gonococcal infection here is not reliably eradicated by single-dose therapy. In MSM, swabs for gonorrhoea and chlamydia should be taken from the rectum.


This depends on local epidemiology and the availability of diagnostic resources. Treatment is often presumptive, with prescription of multiple antimicrobials to cover the possibility of gonorrhoea and/or chlamydia. This is likely to include a single-dose treatment for gonorrhoea, which is desirable because it eliminates the risk of non-adherence. The recommended agents for treating gonorrhoea vary according to local antimicrobial resistance patterns (p. 422). Appropriate treatment for chlamydia (p. 423) should also be prescribed because concurrent infection is present in up to 50% of men with gonorrhoea. Non-gonococcal, non-chlamydial urethritis is treated as for chlamydia.

Patients should be advised to avoid sexual contact until it is confirmed that any infection has resolved and, whenever possible, recent sexual contacts should be traced. The task of contact tracing – also called partner notification – is best performed by trained nurses based in GUM clinics; it is standard practice in the UK to treat current sexual partners of men with gonococcal or non-specific urethritis without waiting for microbiological confirmation.

If symptoms clear, a routine test of cure is not necessary, but patients should be re-interviewed to confirm that there was no immediate vomiting or diarrhoea after treatment, that there has been no risk of re-infection, and that traceable partners have sought medical advice.

Genital itch and/or rash

Patients may present with many combinations of penile/genital symptoms, which may be acute or chronic, and infectious or non-infectious. Box 15.3 provides a guide to diagnosis.

image 15.3   Differential diagnosis of genital itch and/or rash in men

Likely diagnosis Acute or chronic Itch Pain Discharge (non-urethral) Specific characteristics Diagnostic test Treatment
Subclinical urethritis Either ± ± Often intermittent Gram stain and urethral swabs As for urethral discharge
Candidiasis Acute image White Postcoital Microscopy Antifungal cream, e.g. clotrimazole
Anaerobic (erosive) balanitis Acute ± Yellow Offensive Microscopy Saline bathing ± metronidazole
Pthirus pubis (‘crab lice’) infection Either image Lice and nits seen attached to pubic hairs Can be by microscopy, but usually visual According to local policy – often permethrin
Lichen planus (p. 1289) Either ± Violaceous papules ± Wickham’s striae Clinical None or mild topical corticosteroid, e.g. hydrocortisone
Lichen sclerosus Chronic ± Ivory-white plaques, scarring Clinical or biopsy Strong topical corticosteroid, e.g. clobetasol
Plasma cell balanitis of Zoon Chronic image ± Shiny, inflamed circumscribed areas Clinical or biopsy Strong topical corticosteroid, e.g. clobetasol
Dermatoses, e.g. eczema or psoriasis Either image Similar to lesions elsewhere on skin Clinical Mild topical corticosteroid, e.g. hydrocortisone
Genital herpes Acute ± image Atypical ulcers are not uncommon Swab for HSV PCR Oral antiviral, e.g. aciclovir
Circinate balanitis Either Painless erosions with raised edges; usually as part of Reiter’s syndrome (p. 1107) Clinical Mild topical steroid, e.g. hydrocortisone


(HSV PSR = herpes simplex virus polymerase chain reaction)

Balanitis refers to inflammation of the glans penis, often extending to the under-surface of the prepuce, in which case it is called balanoposthitis. Tight prepuce and poor hygiene may be aggravating factors. Candidiasis is sometimes associated with immune deficiency, diabetes mellitus, and the use of broad-spectrum antimicrobials, corticosteroids or antimitotic drugs. Local saline bathing is usually helpful, especially when no cause is found.

Genital ulceration

The most common cause of ulceration is genital herpes. Classically, multiple painful ulcers affect the glans, coronal sulcus or shaft of penis (Fig. 15.2), but solitary lesions occur rarely. Perianal ulcers may be seen in MSM. The diagnosis is made by gently scraping material from lesions and sending this in an appropriate transport medium for culture or detection of HSV DNA by polymerase chain reaction (PCR). Increasingly, laboratories will also test for Treponema pallidum by PCR.

In the UK, the possibility of syphilis or any other ulcerating STI is much less likely unless the patient is an MSM and/or has had a sexual partner from a region where tropical STIs are more common. The classic lesion of primary syphilis (chancre) is single, painless and indurated; however, multiple lesions are seen rarely and anal chancres are often painful. Diagnosis is made in GUM clinics by dark-ground microscopy and/or PCR on a swab from a chancre, but in other settings by serological tests for syphilis (p. 420). Other rare infective causes seen in the UK include varicella zoster virus (p. 316) and trauma with secondary infection. Tropical STI, such as chancroid, LGV and granuloma inguinale, are described in Box 15.12 (p. 424). Inflammatory causes include Stevens–Johnson syndrome (pp. 1264 and 1302), Behçet’s syndrome (p. 1107) and fixed drug reactions. In older patients, malignant and pre-malignant conditions, such as squamous cell carcinoma and erythroplasia of Queyrat (intra-epidermal carcinoma), should be considered.

Genital lumps

The most common cause of genital ‘lumps’ is warts (p. 425). These are classically found in areas of friction during sex, such as the parafrenal skin and prepuce of the penis. Warts may also be seen in the urethral meatus, and less commonly on the shaft or around the base of the penis. Perianal warts are surprisingly common in men who do not have anal sex.

The differential diagnosis includes molluscum contagiosum and skin tags. Adolescent boys may confuse normal anatomical features such as coronal papillae (p. 412), parafrenal glands or sebaceous glands (Fordyce spots) with warts.

Proctitis in men who have sex with men

STIs that may cause proctitis in MSM include gonorrhoea, chlamydia, herpes and syphilis. The substrains of Chlamydia trachomatis that cause LGV (L1–3) have been associated with outbreaks of severe proctitis in Northern Europe, including the UK. Symptoms include mucopurulent anal discharge, rectal bleeding, pain and tenesmus.

Examination may show mucopus and erythema with contact bleeding (p. 412). In addition to the diagnostic tests on page 412, a PCR test for HSV and a request for identification of the LGV substrain should be arranged if chlamydial infection is detected. Treatment is directed at the individual infections (see below).

MSM may also present with gastrointestinal symptoms from infection with organisms such as Entamoeba histolytica (p. 367), Shigella spp. (p. 345), Campylobacter spp. (p. 342) and Cryptosporidium spp. (p. 369).

Presenting problems in women

Vaginal discharge

The natural vaginal discharge may vary considerably, especially under differing hormonal influences such as puberty, pregnancy or prescribed contraception. A sudden or recent change in discharge, especially if associated with alteration of colour and/or smell, or vulval itch/irritation, is more likely to indicate an infective cause than a gradual or long-standing change.

Local epidemiology is particularly important when assessing possible causes. In the UK, most cases of vaginal discharge are not sexually transmitted, being due to either candidal infection or bacterial vaginosis (BV). World-wide, the most common treatable STI causing vaginal discharge is trichomoniasis; other possibilities include gonorrhoea and chlamydia. HSV may cause increased discharge, although vulval pain and dysuria are usually the predominant symptoms. Non-infective causes include retained tampons, malignancy and/or fistulae.

Speculum examination often allows a relatively accurate diagnosis, with appropriate treatment to follow (Box 15.4). If the discharge is homogeneous and off-white in colour, vaginal pH is greater than 4.5, and Gram stain microscopy reveals scanty or absent lactobacilli with significant numbers of Gram-variable organisms, some of which may be coating vaginal squamous cells (so-called Clue cells, Fig. 15.3), the likely diagnosis is BV. If there is vulval and vaginal erythema, the discharge is curdy in nature, vaginal pH is less than 4.5, and Gram stain microscopy reveals fungal spores and pseudohyphae, the diagnosis is candidiasis. Trichomoniasis tends to cause a profuse yellow or green discharge and is usually associated with significant vulvovaginal inflammation. Diagnosis is made by observing motile flagellate protozoa on a wet-mount microscopy slide of vaginal material.

Apr 9, 2017 | Posted by in GENERAL SURGERY | Comments Off on Sexually transmitted infections

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